Link arm suspension

ABSTRACT

A linkage in an electro-mechanical shaker. The linkage has link arms which have two end members coupled to a center member. The three members provide three pivoting points in an axial direction and prevent lateral movement between the relatively movable structures to which they are attached.

BACKGROUND OF THE INVENTION

The present application is a continuation application of U.S. Ser. No.859,609, filed May 5, 1986, and now is abandoned which was filedconcurrently with U.S. Pat. applications, Ser. No. 859,620, , filed May5, 1986, and now Pat. No. 4,715,229 and assigned to the assignee of thepresent application.

1. Field of the Invention

The present invention relates to the field of mechanical shakers andmore specifically to electromagnetically driven armature shakers.

2. Prior Art

There are a considerable number of shakers that are well-known in theprior art. These shakers are used to mechanically shake an item for thepurpose of diagnostically testing responses to certain driving forces.The item is physically attached to a moving portion of a shaker and whenthe shaker is activated, the item is subjected to a variety of testconditions. The moving portion of the shaker is typically driven by aforce which may be continuous, cyclical or impulsed.

One class of these shakers employs the use of an electrodynamicallydriven armature to provide the shaker's mechanical movement. Typically,a housing unit contains a stationary field coil which is connected to anexternal power source. A freely moving armature located within thehousing contains an armature coil which is driven by a power amplifier.The armature coil is fixed to the shaking portion of the unit, such asan armature frame.

By providing a varying drive signal from the amplifier to the armaturecoil, the armature will respond and move accordingly due to a change inthe electromagnetic field. The size and direction of the shaker forceare determined by the strength of the driving signal from the poweramplifier and the power applied to the stationary field coil.

A variety of platforms or tables are normally coupled to the armature,wherein the item to be subjected to testing is mounted onto the table byfixed means, such as bolts, screws, etc. The platform or table isusually constructed from a hard substance, such as metal, to preventdeformation of the platform which will interfere with the resultanttesting.

One side-effect from using such an armature frame is the generation ofunwanted frequency components from the mechanical movement of the shakerarmature. These unwanted frequencies are generated as a result ofoscillations created within the moving metal. Such oscillations finallyreach a peak resonant frequency of the particular material in motion andtend to have disruptive effects by producing undesirable additionalfactors during the testing cycle. A number of types of resonance areencountered in prior art armature frames. One is the telescopingresonance associated with the height of the table and the other is thebending resonance associated with the mass/stiffness distribution of thetable.

Another problem encountered in prior art shakers is the stress placed oncentral armature shaft bearings. Typically, an armature is placed in theshaker housing, such that the armature coil windings fit within thecircumference of the field windings. A shaft attached to the armatureframe couples the armature to the housing, but, because the armaturerequires movement, a surface having a low coefficient of friction isnecessary.

To mechanically couple the armature shaft to the shaker housing, abearing is normally used. Metal roller or ball bearings provide a lowercoefficient of friction yet have the strength to support a substantialload. Further, because most armatures only have linear movement (up anddown motion), prior art linear motion bearings have been used. One suchlinear motion ball bearing is disclosed in U.S. Pat. No. 3,900,233,wherein several linear ball bearing tracks have been designed in theinterior wall of the bearing housing. However, such a track designlimits the loading factor on the ball bearings, because each track mustbe spaced so as to allow for the placement of the non-loading returntrack.

A further problem is associated with means to stabilize the shakerarmature during operation. Typically, an armature shaft is smaller indiameter in comparison to the diameter of the armature. To prevent tablewobble, some retainer means are needed to support the armature. Priorart methods have used springs and rubber bushings, if any support wereused at all.

What is needed then is an improved shaker assembly having an armaturewhich provides a test result which is more independent of the resonantfrequencies encountered in the equipment, a bearing which allows abetter load transfer at a reduced coefficient of friction, and asupporting mechanism which produces high lateral load capability andlateral stiffness with little vibration interference, if any.

SUMMARY OF THE INVENTION

An electro-mechanical shaker apparatus utilizing a novel design isdisclosed. A fixed field winding and a moveable armature provide theelectrodynamic coupling for axially moving an armature table which isfixed to the armature coil. The armature assembly is held in position bya center shaft. The shaft is placed within a recirculating bearing whichprovides a low coefficient of friction when the armature is driven.

The armature frame is comprised of flat, circular, thin upper and lowerplates and a middle-section between the two plates. The height of thearmature frame in the armature raises any telescoping resonantfrequencies encountered. The bending resonant frequencies areeffectively shifted above the testing spectrum of frequencies also bythe laminated design of the armature frame. The top and bottom platesare constructed of materials having a higher modulus of elasticity,while the middle-section is constructed from materials having a lowerdensity.

The recirculating bearing includes a housing which includes a pluralityof return channels located concentric to the inner wall of the housing Aplurality of balls are positioned between the shaft and inner wall ofthe housing, as well as in the channels. Top and bottom retainers,having recessed areas which permit the balls to move from the interiorposition next to the shaft to one of the channels, are placed to enclosethe balls within the housing. As the shaft moves axially, the ballsrecirculate through the channel. Because there are no movementrestrictions to balls located in the interior position next to theshaft, the bearing may also be used for rotational movement of theshaft.

A linkage system attached to the upper portion of the armature and theshaker housing reduces wobble of the armature. The linkage system iscomprised of a plurality of link arms. Each link arm includes two endmembers coupled to a common center member, wherein the three membersprovide three pivoting points in an axial direction of the shaft, butprevent any lateral movement. The pivoting action of the link armfurther compensates for the change in the physical distance of the shaketable from the shaker housing support as it moves axially.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a pictorial view showing component elements of a shakerapparatus of the present invention.

FIG. 2 is a cross-sectional view of the shaker apparatus of FIG. 1.

FIG. 3 is an enlarged cross-sectional view of a portion of FIG. 1showing a placement of a bearing of the present invention.

FIG. 4a is a cross-sectional view of an armature frame of the presentinvention which is shown in FIG. 1.

FIG. 4b is a plan view of an armature coil of the present inventionwhich is shown in FIG. 1.

FIG. 5a is a pictorial view of a link arm of the present invention.

FIG. 5b is a split pictorial view of the link arm of FIG. 5a.

FIG. 6a is a cross-sectional view of the link arm of FIG. 5a showing itsstatic state.

FIG. 6b is a cross-sectional view of the link arm of FIG. 5a showing theelongated state in a first direction.

FIG. 6c is a cross-sectional view of the link arm of FIG. 5a elongatedstate in a second direction.

FIG. 7 is a pictorial view of a bearing housing of the presentinvention.

FIG. 8 is a top plan view of the bearing housing of FIG. 7.

FIG. 9 is a pictorial view of the bearing housing of FIG. 7, top andbottom bearing retainers and a shaft which is inserted into the bearinghousing.

FIG. 10 is a cross-sectional view of an assembled bearing shaft, andplacement of balls within the bearing housing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An armature type shaker having an improved armature frame, arecirculating ball bearing and link arm suspension system is described.In the following description, numerous specific details are set forthsuch as specific thicknesses, etc. in order to provide a thoroughunderstanding of the present invention. However, it will be apparent toone skilled in the art that the present invention may be practicedwithout these specific details. In other instances, well-knownstructures have not been described in detail in order not tounnecessarily obscure the present invention.

Referring to FIGS. 1 and 2, a shaker assembly 10 is shown. A housing 11,having an outer ring 12 and inner ring 13, houses field winding 14 whichresides in concentric circles between the two rings 12 and 13. Housing11 has center opening 16 which houses bearing 17 and armature shaft 18.A circular cover 15 in the shape of a ring is placed onto housing 11 toenclose field winding 14. Cover 15 rests atop ring 12 and over fieldwinding 14 leaving opening 19 such that the combination of ring 12 andcover 15 is at approximately equal height as ring 13. The materialconstruction of housing 11, cover 15 and field winding 14 is well-knownin the prior art.

An armature coil assembly 20 comprised of a circular looping of armaturewinding 21 is inserted into opening 19. Armature coil 20 resides withina circle formed by field coil 14 and cover 15, and ring 13 resideswithin armature coil 20. Armature coil 2 does not physically touchmembers 13, 14 and 15 so that armature coil 20 may freely move in anaxial direction (up and down in the drawing) within opening 19. Byapplying a varying driving signal to the armature coil 20, it can move(shake) in response to the driving signal in an axial direction shown byarrows 22. A variety of prior art armature coils may be used forarmature coil 20, however, in the present invention a special armaturecoil 20 was designed to mate directly onto armature frame 30.

FIG. 3 is an enlargement of a portion of FIG. 2 and illustrates theplacement of members within central openings 16. Referring to FIGS. 1, 2and 3, armature coil 20 is supported to housing 11 by center shaft 18and bearing 17. The shaft 18 has an upper lip 23 which is bolted ontothe center hub 26 of armature frame 30 by bolts 27. It will be notedthat, alternatively, bolts 27 may be reversed such that the bolts areinserted from the top of the armature frame, through center hub 26 andupper lip 23. The shaft 18 is inserted into central opening 16 ofhousing 11. A bearing 17 having recirculating balls 31 makes contactwith a portion of the shaft 18.

A bottom shaft member 32 of the shaft 18 fits into diaphragm 33 which ismade from a flexible material, such as rubber. Diaphragm 33 is held inplace between support members 35 and 36 which are joined together bybolt 37. Diaphragm 33 also has a raised portion 34 which surroundsbottom shaft member 32 and acts as a spacer for a gap 38 between bottomshaft member 32 and support members 35 and 36. An air filled area 40below the diaphragm 33 forms a piston. The weight of added test loadsattached to the armature frame 30 may be compensated by the introductionof pressurized air into area 40. The introduction of pressurized airinto area 40 by openings 41a permits the selective centering of thearmature coil axially. An air opening 41b provides a vent to theexternal atmosphere.

The bearing 17 is held in place by bearing support members 42 and 43which clamp the bearing 17 such that balls 31 make contact with shaft18. Bearing support member 43 is coupled to support member 36 by bolts44 and bearing support member 42 is coupled to ring 13 of housing 11 bybolts 45. The bearing 17 is held in place against a shaft 18 such that ashaft 18 moves axially, the balls 31 provide the load transfer fromshaft 18 to ring 13 of housing 11. Balls 31 also provide low resistancefor movement of shaft 18 and position shaft 18 to move in an axialdirection within central opening 16. Members 35, 36, 42 and 43 may bemade from any number of hardened materials, such as metal, plastic,etc., and bolts 27, 37, 44 and 45 may be of a variety of commerciallyavailable bolts.

In the preferred embodiment, a constant DC voltage is impressed acrossfield winding 14 and a varying driving signal is impressed acrossarmature winding 21 to control the force generated in armature coil 20(control lines and amplifiers are not shown in the drawing). Thearmature frame 30 which is fixed onto the armature coil 20 moves inunison to the armature coil 20. The shaft 18 attached to the armatureframe 30 moves within bearing 17 wherein bearing 17 provides a lowfriction of mechanical coupling of shaft 18 to housing 11.

To prevent wobble at the upper extreme of armature frame 30, a link arm46 is used to restrict any movement other than in the axial direction.Although only three link arms 46 are shown in the drawing, any numbergreater than one, may be used. Each of the link arms 46 is fixed ontoarmature frame 30 and also to individual stanchions 47 which are fixedonto cover 15. A protective covering 48 attached to cover 15 and housing11 encloses link arm 46 and stanchions 47. A degauss coil 49 is attachedto the inside of cover 48 and provides reduced stray magnetic fieldabove armature frame 30.

Although the preferred embodiment describes the basic elements in aspecific style and configuration, a variety of prior art armature typeshakers may be used.

Armature Frame

Referring to FIGS. 1, 4a and 4b, the armature frame 30 and armature coil20 is shown. Armature frame 30 is comprised of a top plate 51, bottomplate 52 and middle section 53. The preferred embodiment utilizescircular plates 51 and 52, however, the shape of the plates 51 and 52may be adapted to meet other shaker designs. Plate 51 includes tappedopenings 54 for bolting on items to be shaken.

The middle section 53 is also of a circular shape such that upperportion 55 couples to top plate 51 and lower portion 56 couples tobottom plate 52. Middle section 53 has a hollow core 57 and ribs 58about the outer periphery. The area 59 between the ribs are devoid ofany material to allow middle section 53 to basically have a ribbeddesign.

Although the size of the plates 51 and 52 are discretionary, thepreferred embodiment has the top plate 51 of a larger diameter thanbottom plate 52. The middle section 53 has the upper portion 55 andlower portion 56 at different diameters to correspond to plates 51 and52, respectively. Ribs 58 are tapered to compensate for this differencein diameter. The two plates 51 and 52 are coupled to mid-section 53 bybolts 60 and adhesive, although any other equivalent fastening systemwill work. The armature coil 20 is coupled to bottom plate 52 also bybolts 61. When mounted together, armature frame 30 and armature coil 20are a single unit as shown in FIG. 1.

To raise the frequency of the undesirable effect of the telescopingresonance, the frame 30 is constructed to have a table height 62 whichis shorter than prior art tables. Th singular design of combiningarmature frame 30 and armature coil 20 also reduces the physical heightof the moving elements from prior art armature coil and framecombinations, thereby further aiding in raising the frequency oftelescoping resonance. The shorter height 62 raises the frequency of thetelescoping resonance so that the telescoping resonance lies above thetest frequency range and does not interfere with the testing. However,as height 62 is made shorter, a bending resonance associated with themass and physical properties of the materials become more significant.The bending resonance has the effect of non-uniform acceleration atdifferent points of the frame 30, thereby causing distorted testreadings.

The frame 30 of the present invention does not completely remove thebending resonances, but instead increases the resonant points tofrequencies which are higher than the test spectrum. Most shaker testingis achieved within a frequency spectrum of D.C. to 2000 Hz. Typicalprior art armature frames, especially those having shortened height (asin the case of the table 30 of the preferred embodiment), will havebending resonances within the D.C. to 2000 Hz spectrum. The design ofthe present invention causes these bending resonance frequencies toshift to a point above this spectrum. Ideally such frequency shifting isachieved by using a low density-high elastic material, such asberyllium, but the cost is usually prohibitive for commercial sales ofberyllium armature frame.

The frame 30 of the present invention achieves this shifting of thebending resonant frequencies by utilizing a laminated design which has ahigher modulus material on the outside and a lower density honey-combedmaterial on the inside. By using the laminated/honeycombed design, morecommon and less expensive materials may then be used to provideequivalent results.

The armature frame 30 uses a thin top plate 51 which has a thickness ofapproximately 1/8 inch at the outer edge 63 and 1 inch near the center64. Bottom plate 52 is also thin having a thickness of approximately 1/8inch at the outer edge 65 and 1 inch near the center 66. The plates 51and 52 have tapered thicknesses to provide more bending support in thecenter 64 and 66.

The plates 51 and 52 have a high Young's modulus of elasticity while themiddle section 53 is constructed of material having low density. Thepreferred embodiment uses steel for plates 51 and 52 and magnesium forsection 53. It is known that magnesium, steel and aluminum haveapproximately the same density to modulus ratio which results in thethree materials having approximately the same resonant frequencies.Steel was chosen for plates 51 and 52 due to its higher Young's moduluswhile magnesium was chosen for middle section 53 for its low density.Use of the multi-materials construction in combination with the taperedribbed design of middle section 53 shifts the resonating points of frame30 bending resonances to frequencies above the 2000 Hz test spectrum.The design of the preferred embodiment has been finally trimmed whereinthe armature frame 30 can operate up to 3000 Hz encountering only 2bending resonances.

Therefore by using a laminated/honeycombed design having a thin layer ofhighly rigid material on the exterior and a lower density material onthe interior of the honeycombed design, an armature frame whicheffectively removes bending resonances from a spectrum of testfrequencies is achieved.

Link Arm

The link arm 46 of FIG. 1 is shown in more detail in FIGS. 5a, 5b, 6a,6b and 6c. Referring to FIGS. 5a, 5b, 6a, 6b and 6c a link arm 46 isshown comprised of a body fastening 78, linkage or interconnectingmember or first link means 79 and brackets 83 and 84 and threecylindrically shaped or interconnecting member or first link meansshafts 75, 76 and 77. Body 78 has two parallel cylindrical bores 80 and81 along the length 82 of the body 78. Body 78 has an opening 91 forexposing a portion of bore 81. Body 78 also has a second opening 90 forexposing a portion of bore 80. Opening 90 is in a direction 90 degreesfrom opening 91.

The bracket 84, having a base 92 and extension 93, has a cylindricalbore 94 at the end of extension 93 opposite base 92. Extension 93 isinserted into opening 91 until bores 81 and 94 arm aligned, at whichpoint shaft 77 is slideably inserted through both bores 81 and 94 tocouple bracket 84 to body 78. Shaft 77 permits body 78 and bracket 84 torotate about the shaft 77. The linkage 79 having bores 95 and 96 at eachend couples bracket 83 to body 78. Bore 95 is inserted into opening 90until bores 95 and 80 are aligned and then shaft 76 is inserted throughboth bores 95 and 80 to couple linkage 79 to body 78. Body 78 andlinkage 79 freely rotate about shaft 76.

The bracket or support body 83, having a base 97 and bore 85, hasopening 98 which exposes a portion of bore 85. Opening 98 faces in thedirection of opening 90 so that the other end of the linkage of bore 96is inserted into opening 98. Bores 96 and 85 are aligned to permit shaft75 to be inserted through both bores 96 and 85 to couple bracket 83 tobody 78, which freely rotate about shaft 75. Further, each end of shafts75-77 are mounted onto bracket 83 and body 78 by bearings 70. Thebearings may be of any prior art high axial load bearings and ar usedprimarily to transfer lateral loads from brackets 83 to 84.

As used in the shake table of the present invention, bracket 83 isbolted onto plate 51 of frame 30 as shown in FIG. 1. Bracket 92 isbolted onto stanchions 47 of FIG. 1. The link arm 46 permits [pivotalmovement about shafts 75-77 but prohibits any lateral movement along theshafts. Therefore by positioning a plurality of link arms 46, the upperwobble of armature frame 30 is reduced. The drawing of FIG. 1 shows onlythree such link arms but any number greater than one may be used. Ifonly two link arms 46 are used, the two must be placed in such a way sothat a pivotal movement of one link arm is opposed by the lateralpositioning of the second link arm (that is, the two link arms must notbe placed 180 degrees apart). FIG. 1 shows a placement of adjacent linkarms where the lateral direction of one of the link arms is in otherthan parallel relation with that of another of the link arms.

FIGS. 6a, 6b and 6c illustrate another advantage of the link arm 46. Asshake table 30 of FIG. 1 moves axially any upper end support elementsexperience a change in the linear distance between its static state andits stretched state (foreshortening). Where FIG. 6a shows the staticstate of link arm 46 having axes 88 and 89 at right angles to eachother, FIG. 6b illustrates the foreshortening encountered. Link arm 46by pivoting at the three shaft centers 71, 72 and 73 compensates for theforeshortening without placing additional load on the armature frame 30.Axis 88 shifts to 88a and axis 89 shifts to 89a. FIGS. 6c illustratesthe alternative case where armature frame 30 moves in the oppositedirection and again encounters foreshortening. Link arm 46 compensatesagain by shifting axis 88 to 88b and axis 89 to 89b.

Although the preferred embodiment is described in specific detail, it isto be noted that the novelty of the invention resides in the two bracketends of the link arm being coupled by three pivoting points. Further,although the link arm 46 is presented to alleviate the foreshorteningproblem encountered on shake tables, it is readily apparent that thelink arm may be used in other applications without departing from thespirit and scope of the invention. Also, the material used forconstructing the link arm is of metal in the preferred embodiment,however, any of a variety of materials may be used.

Thus an improved linkage mechanism has been described which permitspivotal movement in one direction but opposes lateral movement has beendescribed.

Recirculating Bearing

Referring to FIGS. 7 and 8, a bearing body 100 of the bearing 17 of FIG.1 is shown. Body 100 is circular in shape and has a bearing housing 101surrounding an interior channel element 102 and in turn is surroundedexternally by casing 103. Interior channel element 102 includes aplurality of elongated return channel openings 104, which passcompletely through element 102. Further, element 102 is recessed belowthe two end surfaces 105 of housing 101.

Also, referring to FIG. 9, bearing body 100 is shown with retainers 106and 107 and shaft 109. Once the shaft 109 has been inserted through thebearing 17, retainer 107 is fixed to housing 101 by screws (not shown),housing 101 having tapped holes 108 for accepting the screws. Thenspherical balls 110 are inserted into channels 104 and between shaft 109and interior element 102 as shown in FIG. 10. In he preferredembodiment, retainers 106 and 107 are designed to correspond to members42 and 43 of FIG. 3, respectively.

Referring to FIGS. 9 and 10, shaft 109 is shown surrounded by aplurality of balls 110. When the shaft 109 moves axially (as in the casewith shaft 18 of FIG. 1), the balls 110 will also roll in relatively thesame direction, thereby presenting a lower coefficient of friction toshaft 109. As the shaft 109 moves axially, balls 110 first move along awall 114 and recirculates through channels 104 as shown by arrows 113.The recirculation is possible because the retainers 106 and 107 haverecessed areas 121, as well as shortened inner wall 122, which operatein conjunction with recessed portions 123 of element 102 to permit theballs 110 to freely move as shown by arrows 113.

Balls 110 are also capable of providing a low friction surface when theshaft 109 is moved in a rotational direction. Balls 110 will move in arotational direction as the shaft 109, as shown by arrows 115.Therefore, the shaft 109 may move linearly, rotationally, or acombination of the two motions. The design of the bearing 17 allows anygiven ball 110 to cycle through an of the channels 104. The loadtransfer is accomplished by the balls 110 in contact with the shaft 109and stanchions 120 which are located between channels 104. The arrows111 and 112 show the route of the load transfer from shaft 109 tohousing 101.

A significant advantage of this design resides in its ability tosimultaneously perform as a low friction bearing for both linear androtational movement of the shaft. Although the shaker of the preferredembodiment only moves linearly, the use of the bearing is notconstrained to this specific application. Unlike prior art linearbearings, the bearing of the present invention allows more shaft surfacearea contact with balls 110 allowing for a more even distribution of theload transfer from the shaft 109 to bearing 17.

Further, because more surface area of the shaft 109 makes contact withballs 110, the load transfer 111 is accomplished across a larger numberof balls 110 than prior art bearings. The larger number of balls 110making contact to shaft 109 permits higher load ratings or for the samerating, allows the balls 110 to be constructed of lighter load bearingmaterial, such as plastic, whereas prior art designs required higherload transfer requirements per ball for a given diameter shaft.

Thus a recirculating bearing having a much higher load capability andthe ability to perform as a bearing for simultaneous linear androtational motion is disclosed.

Although the present invention has been described with reference toFIGS. 1-10, it will be apparent to one skilled in the art that theteachings of the present invention may be used in a variety of otherapplications.

I claim:
 1. An apparatus comprising two relatively reciprocating membersand means to control the movement thereof along an axis ofreciprocation, said means comprising:a plurality of link arm meanscoupling said relatively reciprocating members and being arranged sothat t least one of said plurality of link arm means is disposed inother than diametrically opposed relationship with at least another neof said plurality of link arm means such that a lateral direction ofsaid at least one of said plurality of link arm means is disposed inother than parallel relation with a lateral direciton of said at leastanother one of said plurality of link arm means, each link arm meansincluding, a first support body having a first cylindrical bore disposedtherein and a first opening to expose a portion of said first bore, saidfirst support body having means fixedly coupling it to one of saidrelatively reciprocating members; a second support body having a secondcylindrical bore and a third cylindrical bore disposed therein and beingparallel with said second cylindrical bore; said second support bodyhaving a second opening to expose a portion of said second bore and athird opening to expose a portion of said third bore, said bores beingaxially disposed in parallel to each other and in said lateraldirection; a first interconnecting member having an elongatedintermediate section having first and second ends and wherein said firstend is disposed within said first bore through said first opening andsaid second end is disposed within said second bore through said secondopening and being arranged and constructed such that said first supportbody is rotatable about said first end but restricted from lateral axialmovement along said first end and said second support body body isrotatable about said second end but restricted from lateral axialmovement along said second end; a second interconnecting member having aproximate and a distal end, said proximate end disposed within saidthird bore through said third opening and said distal end fixedlycoupled to the other relatively reciprocating member; fastening meansfor coupling said first, second and proximate ends to their respectivesupport body yet permitting said support bodies to pivot bout said ends;whereby a movable linkage permitting only a desired planar motion ofsaid relatively reciprocating members along the axis of reciprocation isprovided.
 2. The apparatus of claim I, wherein said first opening facesin a direction opposite to that of said second opening, with saidintermediate section of said first interconnecting member beingstraight.
 3. The apparatus of claim 2, wherein said first and secondends are cylindrical in shape such that said first and second ends fitssnuggly into said first and second bores, respectively.
 4. The apparatusof claim 3, wherein said third opening is perpendicularly directedrelative to said first and second openings.
 5. The apparatus of claim 4,wherein said proximate end of said second interconnecting member has acylindrical shape such that said proximate end fits snuggly into saidthird bore.
 6. An apparatus Comprising two relatively reciprocatingmembers and means to control the movement thereof along an axis ofreciprocation, said means comprising:a plurality of link arm meanscoupling said relatively reciprocating members and being arranged sothat at least one of said plurality of link arm means is disposed inother than a diametrically opposed relationship with at least anotherone of said plurality of link arm means such that a lateral direction ofsaid at least one of said plurality of link arm means is disposed inother than parallel relation with a lateral direction of said at leastanother one of said plurality of link arm means, each link arm meansincluding, a first support body having a first cylindrical bore disposedtherein said lateral direction and a first opening to expose a portionof said first bore, said first support body also having means fixedlycoupling it to one of said relatively reciprocating members; such that alateral direction of said at least one of said plurality of link armmeans is disposed in other than parallel relation with a lateraldirection of said at least another one of said plurality of link armmeans. a second support body having a second cylindrical bore and athird cylindrical bore disposed therein in said lateral direction, suchthat all three of said bores are axially parallel in said lateraldirection; said second support body having a second opening to expose aportion of said second bore, said second opening facing in a directionopposite to that of said first opening; said second support body havinga third opening to expose a portion of said third bore, said thirdopening facing in a perpendicular direction to that of said first andsecond openings; a first interconnecting member having an elongatedintermediate straight section, having first and second ends wherein saidfirst end is disposed within said first bore through said first openingand said second end is disposed within said second bore through saidsecond opening, such that said first support body is rotatable aboutsaid first end; a second interconnecting member having a proximate and adistal end, said proximate end disposed within said third bore throughsaid third opening and said distal end fixedly coupled to the otherrelatively reciprocating member; fastening means for coupling saidfirst, second and proximate ends to their respective support body yetpermitting said support bodies to pivot about said ends; whereby saidrelatively reciprocating members are prohibited from moving along otherthan the axis of reciprocation.
 7. An apparatus as defined by claim 6,wherein said first, second, and proximate ends are cylindrical in shapeto fit snuggly into said first, second and third bores, respectively. 8.An apparatus as defined by claim 7, wherein said third bore is disposedoutside of a plane formed by said first and second bores.
 9. Anapparatus as defined by claim 8, wherein said fastening means includingshafts, said first, second and proximate ends each having a shaftdisposed laterally throughout and the ends of search shaft coupled tosaid respective support bodies.
 10. An apparatus as defined by claim 9,wherein ends of each of said bores are open for insertion of saidshafts.
 11. An apparatus as defined by claim 10, wherein each of saidshaft ends is mounted in a bearing for coupling to said support bodies.